/Engine/Plugins/Runtime/AR/Google/GoogleARCore/Source/GoogleARCoreBase/Public/GoogleARCoreTypes.h
Describes the possible tracking failure reasons in ARCore.
enum EGoogleARCoreTrackingFailureReason { None = 0, BadState = 1, InsufficientLight = 2, ExcessiveMotion = 3, InsufficientFeatures = 4, }